Electrical polymer insulators are used in power transmission and distribution systems to provide mechanical support for conductors and provide electrical insulation between the high voltage conductors and grounded tower structures. A corona protection device is located at the line end and/or the ground end of the insulator and eliminates the corona discharge from the insulator. Elimination of the corona discharge protects the surface of the insulator from polymeric material deterioration caused by electrical stress. Additionally, eliminating the corona discharge reduces television and/or radio noise created by the corona discharge.
One of the problems with conventional corona protection devices is the number of parts required to assemble the corona protection device, thereby increasing the manufacturing costs. Additionally, an installer must transport more parts to a job site, which decreases the speed and efficiency with which the corona protection devices may be installed. Since existing corona protection devices require various parts in order to completely assemble the device, if one part is lost or missing, the device cannot be properly assembled. Thus, an installer must make a return trip to finish installation of the corona discharge device. A need then exists for a collar assembly having few parts, thereby reducing manufacturing costs and providing quick installation.
Other problems with existing corona protection devices involve poor seals being formed between the corona protection device and the insulator, as well as the corona protection device being poorly secured to the insulator. Inadequate seals and connections to the insulators result in a highly ineffective corona protection device, often resulting in failure of the corona protection device. Thus, a need exists for a collar assembly having a good seal and connection to the insulator.
Examples of conventional corona protection devices include U.S. Pat. No. 2,867,682 to Smith et al.; U.S. Pat. No. 4,198,538 to Lusk; U.S. Pat. No. 5,488,199 to Selsing et al.; U.S. Pat. No. 6,265,669 to Richards; U.S. Pat. No. 6,388,197 to Zhao et al.; the subject matter of each of which is hereby incorporated by reference.
Conventional external metal collars clamp down on a cylindrical polymer surface to create a void in the sealing system. Accordingly, a need exists for an improved insulator collar assembly having a metal fitting and a rubber housing forming a compression seal to an external stationary cylindrical metal element.